How long has 3-D technology been around? Most of us might think of crowds of teenagers in a 1950's movie house watching Bwana Devil in 3-D. But 3-D technology made its first appearance on the scene in 1838 with the first stereoscope(体视镜). And the first actual 3-D movie was a 1903 film called Le Ariveed'un Train.

    Although it has such a long history, the technology has still remained based on one simple principle—to make 3-D effects you must find a way to project two slightly different pictures to each eye. Modern 3-D technology works by rapidly flickering(闪动)two versions of the movie and projecting them onto each eye. The brain does the rest of the work, combining the two pictures together into one and giving the show the appearance of depth, the third dimension.

    But does this exposure, especially long exposures, cause harm to the child's developing brain and visual system? Unfortunately, long-term studies on new flicker digital 3-D technology and children aren't yet available. We do not know if regular or daily 3-D viewing over years affects the developing visual system, although older 3-D methods basically do the same thing and are not considered harmful.

    The question of possible harm in modern 3-D use in TV is really based on two facts: the amount of time children will now be watching 3-D TV each day and the sensitivity some children show in reaction to 3-D viewing. It is difficult to make actual lab studies of longer term 3-D viewing in children because of the possible harm of the experiment. Researchers will have to wait until 3-D TV technology is already in the marketplace for a number of years, then check heavy 3-D TV watchers and compare them with non-watchers.

    With a 3-D television technology in the home, we will soon be able to answer the question of whether or not longer and more frequent periods of 3-D exposure cause more changes in the visual system. We may find that the bigger problem is the introduction of a new technology that leads to even more time spent on TV rather than playing outdoors.

    This column is part of a series on websites that are useful for English language learning.

Activities for ESL Students

    Includes various types of tests, exercises and puzzles designed to help people studying English as a second language（ESL）.The activities include grammar, vocabulary and idiom tests at easy, medium and difficult levels. The specially designed Chinese-English vocabulary tests can help Chinese memorize English words.

http://a4esl. org/

Interesting Things for ESL Students

    Contains a comprehensive list of audio clips（听力剪辑）from the Special English programs of Voice of America（VOA）.The list covers news of all kinds on VOA. The listening and vocabulary exercises and the word list designed with the clips will help English learners improve listening ability and increase vocabulary.

http://www.manythings.org/voa/

World-English

    This site provides a list of radio or TV channels offering English news clips. It includes the BBC radio program clips from England, CNN and ABC news clips from the US, and other news clips from other English-speaking countries. Click on the links and you will be taken to channels where you can listen to clips. This is a good way to practice listening.

http://www.world-english.org/listening.html

Listen to English

    Offers a large number of materials for English learners to practice listening. The materials include business English, English literature, history, movies, and politics. Students can improve their English while enjoying the beauty of the English of literature, songs, movies, and news in different countries.

http://eleaston.corn/listen, html

    If you are travelling in Britain, besides so many world-class things to see and do in London, planning a day trip away from it can also be good.

Stonehenge

    Stonehenge consists of a group of large standing stones. The 5,000-year-old stones are one of the world's biggest mysteries(谜) that no one has understood yet. While travelling Stonehenge, you can imagine wildly and decide for yourself how the stones came to be there and why. Although you can't touch the stones, you can walk among them and feel the changes of seasons.

Windsor

    Most people visit Windsor to see Windsor Castle, where the Queen spends most of her time. The castle(城堡) itself could keep you busy for days. The best way to appreciate Windsor Castle is to approach via the Long Walk, a straight road where there are no cars, but you might see some deer.

Oxford

    Oxford is best known for its world-famous university. The large student population keeps the university young and fresh, though there's no shortage of history if you want it. 30 colleges make up the university itself. A tour of the colleges is a must—Harry Potter fans will find many places used in the movies.

Bath

    Founded by the Romans, who used the area's springs to create a spa retreat（水疗中心）, Bath's now the best tourist attraction of Southwest England. Visitors never miss the Roman Bath Complex, which is divided into four main parts—the Bath House, the Sacred Spring, the Roman Temple and the museum, which displays fascinating finds from the historical ruins of the city.

    Johnny Jennings is 86 years old, but he first visited the Georgia Baptist Children's Home when he was 18, and the visit changed his life forever.

    A child ran up to Jennings, begging to be adopted, and it was at that moment that Jennings realized his life's mission. From that day forward, Jennings did everything he could to help, and that turned out to be quite a lot. Since he wasn't ready to adopt a child of his own, he decided to contribute financially. Since he wasn't wealthy, he did so by collecting paper and aluminum (铝) products and cashing them in for money. That may not sound like it would amount to much, but Jennings has donated more than US$400,000 over the past 30 years. That's a lot of paper products.

    Over those 30 years Jennings has become a cornerstone of the children's home.

But how does he get all that paper? Now that people know about his efforts, the paper pretty much comes to him. People drop it off at his house after collecting it through churches, organizations or in their own lives. Jennings also collected pennies, and as they say: A penny saved is a penny earned. Well, he's saved 24 miles' worth of pennies. It's the truth. "84,480 is a mile of pennies," Jennings said. "We finished 24 miles. We had most people from church collecting pennies." Each and every mile was a donation to the church.

    One of Jennings' favorite events is the church's annual meeting, which is when he presents his check each year. During this time, the kids who live in the children's home are also in attendance and he loves the opportunity to spend time with them. Jennings has served on the board for 45-year terms. "I've been a trustee for 20 years," Jennings said. "I'm just part of the family." And what a special family it is, thanks in large part to Johnny Jennings.

    China is known as a state of manners and ceremony. Many proverbs have been passed down from generation to generation such as "polite behavior costs nothing" or "showing respect each other" and so on. For instance, there is an interesting short story. Once upon a time, a man went on a long tour to visit his friend with a swan as a gift. But it escaped from the cage on the way. Though he tried hard, he got hold of nothing but a feather. Instead of returning home, he continued his journey with the swan feather. When his friend received this unexpected gift, he was deeply moved. And the saying "The gift is nothing much, but it's the thought that counts." was spread far and wide.

    Chinese used to cup one hand in the other before the chest as a greeting. This tradition has a history of more than 2, 000 years and nowadays it is seldom used except in the Spring Festival. And shaking hands is more popular. Bowing, as to show respect to the higher level, is often used by the lower like subordinates(下级), students, and attendants. But at present Chinese youngsters prefer to simply nod as a greeting.

    When you start a talk with a stranger, the topics such as weather, food, or hobbies may be good choices to break the ice. For a man, a chat about sports, stock market or his job can usually go on smoothly. Similar to Western customs, you should be careful to ask a woman private questions. However, relaxing talks about her job or family life will never put you into danger. Though Chinese are said to be implicit(含蓄的), they are actually humorous enough to be pleased about the jokes of Americans.

    Eco-friendly Vauban, lied in the southwest part of Germany, has everything－tree-lined streets, perfect houses－but it's missing one urban feature of the last 100 years or so: the car. And Vauban residents(居民) don't mind one bit. Vauban doesn't ban cars entirely. Rather, it just tries to reduce the use of cars by creating “parking-free” and “car-free” living. In Vauban, parking spots are a no-no private property(私人财产). Cars can only be parked in public parking lots, so living without a car saves residents the cost of parking in the public lot. Cars also are prevented from using certain roads and must stick to strict speed limits. With these limitations, fewer than 20 percent of residents own cars. Without cars, bikes are almost religion in this small town. Kids pick them up even before they can ride one. Vauban is about much more than just using two wheels instead of four. In Vauban , residents ride bikes and even receive money from the electric company for selling electricity back to the power grid (电网系统). It's an environmentally-friendly city of the future, with organically grown food, renewable energy, and carbon-neutral homes. And now, with a population of 5,500, it's attracting attention from around the world. Can an eco-friendly city like Vauban be a model for Americans to stop their over-reliance on the cars?

    Sometimes when I watch a news report what's in the back of my mind is what isn't being reported or stressed. While this eco-friendly city is inspiring in that it shows residents getting exercise and fresh air through the majority use of bicycles, as well as good old fashioned walking, common sense would tell you that even for a place like Vauban, Germany, it owes its existence to the cars.

    Do you think that bicycles were able to transport all the construction materials that were needed to build and maintain the eco-friendly homes and businesses in Vauban? It took cars to help build this utopia. It's one of the paradoxes of life that sometimes in order to get away from relying on something like the car, you actually have to rely on that very thing at the beginning and into the foreseeable future to some degree.

    I myself haven't owned a car for more than 14 years, and mostly get around town running, walking, or using public transportation. There are times I wish I had one, since it would make many things easier, but overall I'm glad not to have to deal with the headaches of owning a car, which caused me to get rid of it in the first place. And all the walking and running has helped to keep me fit and healthy.

    To get even close to being like eco-friendly Vauban, Americans will need to absolutely change the way they live. Commuting(乘车上下班) patterns will have to change, public transportation will have to be invested in, and so on. And though ending our love affair with the car will be impossible during my lifetime, we may at least start to see more Vauban-like areas in the USA.

    We can hope that Americans will consider using their feet more to get around, cutting down on pollution, and giving themselves some more exercise.